In packaging container producing equipment for producing packaging containers, into which a content is filled, from sheet-like web, rolled sheet-like web W of rewinder L, which is wound to be roll-like as shown in FIG. 1, is wound back by a windback device, the wound-back sheet-like web W is transferred by web feeding roller 10 and is sent to tube forming device 3 via tension pressing device 2 consisting of a dancer roll (rocking roller) 9, which gives tension to the abovementioned web W at all times, and guide roller 11, wherein the sheet-like web W is reformed to be tubular web W while being formed by forming rollers 14 (only one stage is illustrated in FIG. 1) provided to be multi-staged, and the edges overlapped in the lengthwise direction of the tubular web W are sealed (longitudinally sealed) in the longitudinal direction. Furthermore, after a part of web W is sealed (cross-sealed) in the direction orthogonal to the lengthwise direction of web W, a content is filled into a tubular web W located in the upstream side of the cross-sealed part, and after cross sealing is further carried out at a size equivalent to one container at the abovementioned web, said cross sealed part is cut off, thereby a hexahedral packaging container C is produced, in which the content is filled.
The tube forming device 3 is provided with a filling pipe 5 to fill a tube with a content such as fluid food, etc. and is provided with a pair of seal jaws 7 (only one jaw 7 is illustrated in FIG. 1, two pairs of cross seal jaws 7 are provided so as to vertically move) in order to seal the tubular web W from both the sides of the tubular web W via a drive mechanism (not illustrated) from the main shaft 6 of the packaging container producing equipment.
A pair of cross seal jaws 7 move downwards while pulling downward the tubular web W being transferred. After the seal jaws 7 falls down to an appointed distance, they release the sealing state of web W to cancel the downward transfer force of the tubular web W and move in such a direction of separating each other. Then, the seal jaws 7 are elevated to an appointed distance and repeat a sealing action of the tubular web W again.
At this time, as shown in a detailed view (only one of the pair is illustrated in this drawing) of the cross seal jaws 7 of FIG. 3, the abovementioned cross seal jaws 7 are provided with jaws 7b attached to a horizontal bar 7a, and web is nipped between a pair of jaws 7b to cause a cross sealing to be executed. Furthermore, lug folding flaps 7c rotating in the direction of the arrow A are attached to one of the cross seal jaws 7, wherein while web W is nipped between a pair of jaws 7b, the abovementioned lug folding flap 7c is able to fold lugs Wb formed at the web W.
On the other hand, specified printing patterns and detection marks a (See FIG. 6) such as a straw port for registering positions are provided at appointed intervals on the web W. As using the position of the abovementioned detection mark a as reference, it is necessary to adjust the feeding amount of web W (this is called "mark registration") in packaging container producing equipment so that detection marks a of printing surface of every packaging container C come to an appointed position.
However, since errors in positioning of patterns and straw port when printing on sheet-like web and changes of the feeding amount of web W due to defective rotations of rollers in the packaging container producing equipment are unavoidable, it is necessary to register the abovementioned marks at all times while the packaging container producing equipment is in operation. If the feeding amount enters such a state where it can not be adjusted by registering the abovementioned marks, there are cases where packaging containers C which are the final formed products can not be formed to their object shape.
Since ever, the mark registration is, as shown below, carried out by combination of (1) a method of adjusting the folding amount of web W in its transfer direction and (2) a method of adjusting the degree of tension applied to web W being transferred.
(1) Method of adjusting the folding amount of web W in its transfer direction (See FIG. 8)
The feeding amount of web W in the transfer direction is classified into the following two stages of action, wherein the first action is to adjust the feeding amount of web W in the transfer direction by a pulling intensity of web W, and the second action is to adjust the folding angle of lug part formed on web W. By combining these methods, the web W is transferred in the web transfer direction.
That is, mechanical feeding action of web W in the transfer direction consists of the following two actions shown in FIG. 8.
1 By the sealing part of web W being nipped at both sides by a pair of cross seal jaws 7, the mechanical feeding action is carried out by pulling the web W equivalently to the moving amount of the cross seal jaws 7 in the web transfer direction (See FIG. 8(a)). PA1 2 The shape of web W taken along the line A--A in FIG. 8(a) is as shown in FIG. 8(b), and the lug part web Wb (See FIG. 11) is folded, as shown in FIG. 8(c), from both sides of tubular web W in the right angle direction with respect to the cross seal part Wa (See FIG. 11) formed by the abovementioned action 1.
The abovementioned actions 1 and 2 are basically for applying cross sealing to tubular web W, folding a lug part formed at the cross sealed part and finally forming a hexahedral body. However, by adjusting the folding angle of the lug folding flaps 7c, it is possible to adjust the feeding amount of web W.
An appointed amount of web W is sent in the abovementioned action 1, and the usual feeding action and corrective feeding action of web W, which will be described later, are carried out in the abovementioned action 2.
A detector 19 for detection mark a such as a specified printing pattern, straw port, etc. is installed, as shown in FIG. 6, at a specified point established in advance in packaging container producing equipment. Data signals detecting a detection mark a of web W of the abovementioned detector 19 and cam rotation angle signals of an encoder 22 for detecting the rotation angle of the main shaft 6 to which a cross seal jaw drive cam 24 is attached are inputted into a control device 23. The rotation angle of shaft 6 of the cam 24, which is secured at the point when the data signal of the abovementioned detection mark a is read, is regarded as a detection angle of the a deviation between the detection mark a in the abovementioned control device 23, and the detection angle of the abovementioned detection mark a and the reference angle established in advance is obtained, wherein a value responsive to the deviation is outputted, via a solenoid valve 25, to the pneumatic cylinder 26 for adjusting the folding amount of lug folding flaps 7c (FIG. 3) of the cross seal jaws 7.
As shown in FIG. 7, lug folding cam 27 is able to take positions 1 and 2 in FIG. 5 by the pneumatic cylinder 26. Since a roller 28 moves on the cam surface when the lug folding cam 27 is at the position 1, the lug folding flap 7c carries out a corrective action of folding to the position shown in FIG. 9(b), and since the roller 28 moves on the cam surface when the lug folding cam 27 is at the position 2), the lug folding flaps 7c carries out a usual feeding action of folding to the position shown in FIG. 9(a).
The lug folding angle of web W of the lug folding flaps 7c is established from a deviation between the detection angle of the detection mark a by the detector 19 and the reference angle established in advance, in such a manner that a usual feeding action which produces a web feeding amount obtained by adding only 0.5 mm to the reference feeding amount is employed until a detection value equivalent to the value obtained by adding only 1.5 mm to the reference feeding amount is obtained as for the web feeding amount, and as the detection value equivalent to a value obtained by adding only 1.5 mm to the reference feeding amount is obtained as for the web feeding amount, a corrective feeding action which produces a web feeding amount obtained by subtracting only 1.0 mm from the reference feeding amount is employed.
In FIG. 9, FIG. 9(a) is a view explaining a usual feeding action of web W and FIG. 9(b) is another view explaining a corrective feeding amount of web W. In the usual feeding action of web W in FIG. 9(a), web W is fed at the initial set value equivalent to the web feeding amount obtained by adding only 0.5 mm to the reference feeding amount (the feeding amount which becomes a reference on design) at a folding angle A.degree. of the lug folding flaps 7c.
Web feeding amount in the usual feeding action=Reference feeding amount+0.5 mm.
Furthermore, the folding angle of the lug folding flaps 7c is changed to angle B.degree. in the corrective feeding action of web W shown in FIG. 9(b) to secure the feeding amount obtained by subtracting only 1.0 mm from the abovementioned reference feeding amount.
Web feeding amount in the corrective feeding action=Reference feeding amount-1.0 mm
As regards the abovementioned web W feeding amounts [-1.0 mm] or [+0.5 mm], the detailed figures are used for only making the explanation more understandable. That is, the usual feeding action and corrective feeding action of the invention are not limited to these figures.
Conventionally, the feeding control of web W was controlled by only the abovementioned usual feeding action and corrective feeding action of the lug folding flaps 7c. For example, where it is assumed that there is no printing error (no slip of the detection mark a) of web W, and there is nothing abnormal in the feeding amount of the feeding roller 10, guide roller 11, etc., as shown in FIG. 10 (a), the folding angle of the lug folding flaps 7c is changed to angle B.degree., as shown in FIG. 9(b), and the action is changed to a corrective feeding action at the point of time (after the usual feeding action is performed two times) when web W is excessively fed 0.5 mm each by the abovementioned usual feeding amount made by the lug folding flaps 7c and web W is excessively fed 1.5 mm which is the allowance of slip from the reference feeding amount.
Web W, the slip of which became 0.5 mm from the reference feeding amount by the corrective feeding action, is caused to enter the usual feeding action again. In a case where there is no slip of the detection mark a such as a printing error of web W and there is nothing abnormal in the feeding amount of feeding roller 10, guide roller 11, etc., the abovementioned corrective feeding amount is carried out once every three feeding actions (See FIG. 10 (a)).
However, herein, since web W is excessively fed 0.5 mm per usual feeding action if a slip of the detection mark a of web W such as a printing error is, for example, +0.5 mm, the slip from the reference feeding amount in total becomes 1.5 mm per usual feeding action, wherein the feeding is changed to a corrective feeding action after the usual feeding action is performed once. Therefore, the corrective feeding action is executed once every two feeding actions as shown in FIG. 10(b). If the control device 23 judges that, in the usual feeding action, a slip from the reference feeding amount became 1.5 mm, the action is changed to the corrective feeding action.
Furthermore, since web W is excessively fed 0.5 mm in the usual feeding action if a slip of the detection mark a of web W is, for example, -0.25 mm each, the feeding action is separated 0.25 mm each from the reference position in one usual feeding action in total, and at the point of time when the slip from the reference feeding amount becomes 1.5 mm, the action is changed to a corrective feeding action. Therefore, as shown in FIG. 10(c), the corrective feeding action is executed once every five feeding actions.
(2) Method of adjusting the degree of tension applied onto web W being transferred In order to accurately cause web W to move an appointed distance without fail by the method (1) of adjusting the web feeding amount by adjustment of the folding angle by the lug folding flaps 7c, it is necessary to give adequate fixed tension to web W by the tension pressing device 2. For example, if the tension of web W is too intensive, a mechanical slip occurs between web W and its feeding members, thereby causing the movemental amount of web W to be decreased. To the contrary, if the web tension is too weak, the web is slackened to cause the web W to be transferred beyond the necessity.
In order to give an adequate tension to web W, tension pressing device 2 is composed of a web W feeding roller 10, a guide roller 11a, a dancer roller 9 disposed therebetween, a pair of rocking arms 12 having the abovementioned dancer roller 12 at its tip end, which causes the dancer roller 12 to rock, a rotation shaft 13 of the rocking arm 12 secured at the base end of the abovementioned pair of rocking arms 12.
The abovementioned mark registration is carried out by combination of the method (2) and the abovementioned method (1).
As described above, a corrective action of the feeding amount is carried out by the lug folding flaps 7c for a slight change (for example, 1% of the prescribed value) of the feeding amount of web W. However, it is necessary that a change (error) of the feeding amount of web W, for example, the average error of each time for 100 pitches of web feeding action equivalent to one packaging container C is less than an appointed value (for example, .+-.0.5 mm or less) and a change (error) of the feeding amount of web per pitch of the web feeding action equivalent to one packaging container C does not exceed an appointed value (for example .+-.1.5 mm).
Furthermore, the more the consumption of roll-like web W becomes, the more frequently occurs a case where a slip of the detection marks a correctable by the abovementioned method (1) of adjusting the folding amount of web in the transfer direction exceeds the permissible range of correction of the mark registration, wherein it becomes impossible to correct the feeding amount of web W.
For example, in three pattern examples shown in FIG. 10(a) through FIG. 10(c), if a slip of the detection mark a from the reference feeding amount, such as a printing error of web W, is +1.0 mm per pitch of the abovementioned actions, the slip exceeds the allowance range of detection error at once, thereby causing faulty containers C to be produced. In some cases, packaging container producing equipment is unavoidably caused to come to a stop. Furthermore, if a slip of the detection mark a is continuously, for example, -0.5 mm or more per pitch, the slip goes beyond the reference feeding amount line (See FIG. 10) equivalent to the reference feeding amount, the correction of the feeding amount of web W becomes impossible.
Furthermore, by repeating the usual feeding action and corrective feeding action through adjustment of folding angle by the abovementioned lug folding flaps 7c, there was such a case where packaging containers C of slightly different shape are produced, the roundness of lug part Wb of web W, for example, is too round, or the corner is too keen.
As regards packaging containers C formed by the corrective feeding action, since the folding degree of the lug part Wb is weaker than the reference value, there is a possibility of producing faulty packaging containers C, that is, faulty products, in which sufficient welding is not carried out in the welding process with the body portion having a rectangular section, which is carried out in the subsequent process regarding the formation of web W. Furthermore, inconvenient folding wrinkles may be produced at the corner parts when the final hexahedral body is formed.
Thus, prior arts have a problematic point by which it is possible to adjust the feeding amount of web W while continuously running the machine since the range of adjustment of the feeding amount of web W is narrow.
Therefore, it is an object of the invention to eliminate the deficits of the prior arts.
It is an object of the invention to quickly eliminate an error of detection mark registrations such as a printing error on web W, and to provide packaging containers, free from any unevenness in shape, for which the range of adjustment of the feeding amount of web W can be widened, the adjustment of the feeding amount of web W can be carried out with the machine running, and the formability of which is further improved.